The CRISPR-Cas9 system demonstrates unparalleled genome editing efficiency in a broad range of species and cell types, but it suffers from concerns related to target specificity. Modified guide RNAs and mutant Cas9 proteins have been developed to reduce off-target editing but, in many cases, the alterations also significantly reduce on-target editing performance. In this presentation, Dr Chris Vakulskas discusses a novel, high-fidelity Cas9 protein that reduces off-target gene editing, while maintaining high on-target activity. Dr Vakulskas presents data from the development of the new Alt-R® S.p. HiFi Cas9 Nuclease 3NLS and describes its usefulness in mitigating unwanted off-target gene editing, without the issues associated with transfection of plasmid DNA.